Load indicating and control apparatus for testing machines



March 28, 1950 F. c. HUYSER 2,502,009

LOAD TNOTOATTNG ANO CONTROL APPARATUS FOR TESTING MAOHTNES Filed Aug. 21, 1944 4 SheeEs-Sheet l FRANCIS C. HUYSER Bym,

ATTORNEY March 28, 1950 F. c. HuYsER 2,502,009

LoAn INDTCATTNG AND CONTROL APPARATUS v FoR TESTING MACHINES Filed Aug. 21, 1944 4 sheets-sheet 2 A .EIIQENEY March 28, 1950 F. c. HUYsER 2,502,009

LOAD INDICATING AND CONTROL APPARATUS FOR TESTING MACHINES Filed Aug. 21, 1944 4 Sheets-Shea?I 5 l IN V EN TOR. FRANCE o. HUYSER ATTORNEY March 2s, 195o Filed Aug. 21, 1944 F. C. HUYSER LOAD INDICATING AND CONTROL APPARATUS FOR TESTING MACHINES l' 4 Sheets-Sheet 4 I N VEN TOR. FRANCIS C. HUYSER BY/ww 65041K ATTORNEY Patented Mar. 28, 1950 LOAD INDICATING AND CONTROL APPARA- TUS FOR TESTING -MACHINES Francis C. Huyser, East Moline, Ill., assigner to American Machine -and Metals, Inc.,`New York, N. Y., a corporation of Delaware Application AugustZl, 1944, Serial No. 550,346

(Cl. lfil-4900 y32 Claims.

This invention relates to machines having a scale beam, Aand in particular to testing machlnes having a load-indicating system which includes a scale beam.

VMore specifically, one aspect of the invention relates to testing machines having a scale beam with means for 'automatically moving the poise in conformity with the varying Stress exerted upon 'a specimen'being tested.

It 'has long been proposed'to automatically baiance scale beams 'by providing poise-moving mechanism set into operation by the swing of the scale beam from its balanc'edposition. While such devices have achieved some success in automatic Weighing scales they have been unsuited to the operation of testing machines. In an `automatic Weighing lmachine the load is read after the poise comes to rest and there is no occasion to read the scale while vthe poise is in movement. In contrast however, in a testing machine, the load is continuously Varying from the inception ofthe test vto the rupture of the specimen and 'the load must be determined at a particular instant vwhile the -poise is in motion To make v'an automatic poise-moving mechanism applicable to a testing machine it is necessary to provide facilities that will move the poise at ythe same rate that the load is changing' so that at each instant the reading indicated by the position of the poise on the scale beam will. be indicative o'f the load on the specimen. This requires a poise-moving mechanism having a range oi speed 'extending up to the most rapid rise in load met in the voperation of the testing machine. Such poise-moving 'mechanisms have not been available.

In a testing machine further diiculty is experienced in securing the desired sensitivity of the machine because 'the mechanism connected with the 'scale beam that initiates movement of the poise mover should not exert upon the scale beam a pressure great enough to appreciably affect the free oscillation of the scale beam, yet must control the iiow of substantial power to the poise lmovei` to secure rapid balancing. Whether the poise-.moving mechanism be electric,

hydraulic or mechanical, a servo mechanism l Weighing machines are not called upon to prom vliethe same accuracy or "the 'same range, .so the servo mechansim of less 'importance in them.-

iii)

Another difficulty met in the design oi an automatic poise-moving mechanism adapted .to a testing` machine results from the inertia of vrthe scale beam. Theinertia of the scale beam is large in comparison to 'the forces tending to 4balance or unbalance the 'scale beam and the natural period of oscillation of the scale .beam is long. If the scale beam becomes unbalanced andthe poise is moved slowly,there is no great difficulty in 'getting the scale beam back into balanced position without kexcessive hunting. As already pointed out, if the poise is to indicate the load instantaneously the poise must be moved at 'a variable rate and sometimes at a relatively rapid rate. Under those vconditions an appreciable length of time will elapse vafter the poise has reached the balancing position until the scale beam will Ahave swung back to its balanced position. During this interval, while the pendulum is slowly swinging back to balanced position, the poise-movingmechanism is still engaged and this causes the poise ytosericusly overshoot its proper position. Not only is the wrong indication thus given by the poise, but the overbalanced scale beam will swing past the balancing position'with considerable inertia, `starting the poise moving back whenit again will overshoot the mark. Thus serious hunting will result which cannctbe damped in the ordinary Way by providing frictional resistance to the free movement of the beam.

The invention provides means which leave the scale beam unrestrained over a narrow range but, after that range is exceeded, the swing of the beam is limited by resilient means. These novel means further provide 'for starting the beam backl toward its balanced 4position before the vpoise has reached its balanced position. rihereby the time between 'the arrival of the poise and .the scale beam at their 'respective balanced positions is so shortened that hunting is almost eliminated.

Since a testing machine may be used for long periods on a -particular project utilizing only a portion of its range it is desirable to provide the machine with .two scales so that the same poise will balance a given load either by moving over a short distance or a long distance on .the scale. This has been accomplished in. the past by changing one or more of the fulcrums in the mechanism. It is desirable however to be able to make the change during the ,progress of test Without `thereby changing the rate of appli cation to the specimen. This is here accomplished by a method .permitting the .gradual shift from one knife edge to another.

It is an object of the invention to provide a.

which. will limit the amplitude of the swing oi the scale beam by moving the poise so rapidly as the swing increases slightly that the unbalanoing forces act upon the scale beam during only a small part of the normal period of oscillation ofthe scale beam.

It is another object of the invention. toprovide a self-balancing system including a scale beam wherein the scale beam has a limited range of free oscillation.

Itis a further object of the invention to provide a self-balancing system including a scale beam wherein the scale beam has a limited range oi free motion and thereafter encounters resilient restraint which will shorten the period of oscilw lation of thel beam when swinging over a wide range. i

It is a further object of the invention to providel a self-balancing system including a scale bea-m wherein the oscillation of the scale beam initiates.

an automatic poise-moving mechanism wherein forces built up by the swing of the scale beam. beyondy a short free-balancing range will assist thepoise in starting the scale beam to swing back toward. the balanced position in advance oi the arrival of the poise at the balanced position in the scale.

It is a iurtl'ier object of the invention to provide a self-balancing system wherein a lever loaded in proportion. to the force being measured reacts against the scale beam at any one of several optional points, permitting a choice of scale ranges.

Itis a further object of the invention to provide a self-balancing system wherein a lever loaded in. proportion to the force being measured reacts against the scale beam at any one of several optional points, and means are provided for grad ually transferring the reaction from one point to another during the progress of the loadmeasuring operation.

It is an object of this invention to provide a seli-balancing system wherein a poise is moved along a scale beam by a hydraulic motor whose movement is controlled by the position of the scale beam relative to its balanced position.

It is a further object of this invention to provide a selfbalancing system wherein a poise is moved along a scale beam by a hydraulic motor whose movement is controlled by a control valve which in turn controlled by a pilot valve.

It is a 'further object of the invention to provide a self-balancing system wherein a poise is moved along the scale beam by a hydraulic motor where in high sensitivity is secured by using a pilot valve of small size actuated by the scale beam to control the control valve for the hydraulic motor and further reducing the restraint imposed upon, the

scale beam by the pilot valve by keeping the,

pilot valve piston in movement relative to its valve body.

It is a further object of the invention to provide a self-balancing system having a poise that 4. is moved along a scale beam by a hydraulic motor governed by a pilot valve of small size actuated by the scale beam to operate the hydraulic motor control valve whereas the restraint imposed upon the scale beam by the pilot valve is further reduced by oscillating the pilot valve piston in the valve body.

It is a further object of the invention to provide a self-balancing system having a poise that is moved. along a scale bea-m by a hydraulic motor wherein movement of the scale beam opens a pilot valve which controls the degree of opening of the control valve, the pilot valve being automatically closed when the control valve has opened to an extent which is relative to the distance the scale beam has moved from its balanced position, thereby determining the rate at which the hydraulic motor moves the poise.

It is a :further object of the invention to provide a selibalancing system having a poise that is moved along a scale beam by a hydraulic motor wherein movement of the scale beam opens a pilot valve which controls the degree of opening of the control valve that is automatically closed when the control valve has opened to an extent which is related to the distance the scale beam has moved from its balanced position, thereby determining the rate at which the hydraulic motor moves the poise wherein the free amplitudel of the scale beam is limited and` resilient means become effective beyond the range to limit the excessive movement of the valve.

Another object of the invention is to provide a testing machine of the kind just described whereev f in if the load is applied to the specimen at .a

rapid rate1 the poise will be movedtowards its balancing position at a rapid rate, whereas, if the load is applied at a slow rate, the poise will also move slowly. f

A further object of the invention is to provide i in a testing machine having a load indicating system of the scale-beam type buffer means for limiting the swing of the beam which are capable oi offering a rapidly increasing resistance as the force tending to unbalance the scale beam in- It is a further object of the invention toreducey the amplitude of the oscillations of the scale beam so radically that even for relatively great un.

. balancing v.forces the motion of the beam remains almost imperceptible, thus largely eliminating the effect of the inertia of the beam.

Still another object of the invention is to provide in a testing machine having a load-indicating system of the scale-beam type a wide range of different travel speeds for the poise in spite of the `lact that the oscillations of the scale beam are radically damped. Other objects and advantages of the invention will appear as the description proceeds, ref' for checking the oscillations of the scale beams Fig. 5 an enlarged view, partly in section, of-V a portion of the scale beam shown in Figs. l and 3;

Fig. 6 is a section on line 6--6 of Fig. 5; andl Fig. 7 is a fragmentary section on line 1--1 of" Fig. 2 showing a vibrating mechanism.

machines in-which` the load-.isfapplie'd hydranlifvv l5".-

callyfand measured by', the pressure' of: thefliquid'i under the pressure#applying-fv ram.'1

C indicates a scale beam having' a' poisean'd.; hydraulic'zmeansffor moving the ipoiseautomatically toa-pos-itionlwhere theheam balances.r

D, shown infoutline :in Figs." 1, .3 Fand: 4', .and in.v detail'y in'-Fig.. 2, indicates-ank automatic.' valves mechanism designed to move `the poisefat a variv ablefr'ateV dependent upon thefdegree of unbal ance present4 when the scale.Y beam has' beenaz thrown. out of balance-by a changein thefload. applied'to thefspecimen.r in artesting machine;v

hiirepresents.meansfor`l limiting the range of.' oscillation: of` the'A scale beam. Twokr forms of. such limiting means' are'shown; one .inFigs 1 and-y 3,; ,andithe other.` in `1liig;.4.-.

Frepresents means-for securing high sensitivity, of the scale by decreasing.thefresistanceofthe automatic valve mechanism tov nfimfernent.=. This .is-:accomplished byfoscillatingv a` pilot valve@ forming part ofiithisv valvemechanism in rits house'Y G denotes'ascale selecting mechanism show-n ingreater detail-in Figs.y 5-and 6. Thiswmeche anism permits establishingvarious scale ranges. anyone of whichithe operator can select. The scalelv beam.- is. graduated in conventional .mane ner `so that .the positionof thepoiseon the beam..l can be. read. Each interval of one scaleonthe beam may have `differentuvalues.dependingy on-`45` the position. of the: scale selecting mechanism'V orA severa-l'l scalesvmay bemarked side"y byside;` on-thescalebeamandthe poise position ready olf` directly on the appropriate scale in terms' of'. iload.. on the specimen.. Thus, whentestsA aret tube performedthat arerknownto involve `only small loads, arelatively great effective length of thescale beam vmay be used assuring that .the indications are of great accuracy. which can be readv easily; .whereas otherA scaleA ranges-.rn ay. bewselected when" the same testing machine is to bevusedhin making testsinvclving. .higher loads# .The'finvention can -be applied. to theautomatic balancingof any-scale beam, or; to the measure@ ment-of any quantityvbyatesting machine. wherethef load. on. the scale beam` varies with-the changes in that. quantity. Thus the inventionv maybe appliedto the'Ineasurementf-ofl a force,- of a` torque, compressionOrtenSiOn. AlthoughH equallyappl-icable toa testing machine-designed tameasure bending, compression.. tension or. toresion, the invention is here illustrated inltloge-ap.im plication to a compression i testing .ymachine such as iszusedi in making tests'. on concreteablocks: oreylinderssy The testing machine shownlhas'a basefI withl anextension 2;- the latter carrying .the loading dicating.l mechanism. Supportedson the base If bygcolumns 41is1afhead3.. ThefcolumnsArmagh begrods which` extend. throughl the; head1.; fandt aree.engagedvv by vnntsw Thei'head: 3f containsaaf cylinder fwithin'a which isa'a ram :orpiston 'I that: exertsffthe. pressure eomth'e-.specimenz Thisfpiston'; has'a stemt ofzreduced crossesection. Conduite.:

9F andV I 0 Ilare providedto` supply 'a .pressure fluid;

such. aszoil, toxthetop: and' the bottom. of` the.: ram l'; The `:function: of conduit IGis` solely to.` return?y the'. ram I to its initial raised positionl when? the pressure. fluid. is'.` withdrawn through'L l conduit4 9 ffromi the upperfportion I I of.. the cylinder '6;.r'elievingzthe upper'sicle of the-ram` 1: fromiluidv pressure.y If desired; the: conduit IIJ-fy may "bef eliminatediand a ramy of'uniform crossse'ction.. may: beffused.` together' fwith a` spring or Whiclipresses; upon: the specimen. The. specie menf is :supported on a l. lower platen. I 4.

.Intthe-:arrangementrshownrin Fig. l the loadi applied" to the specimen' l-3 is determined by measuring-the pressure which the: specimen exerts-f` uponthe'lowenplaten. ILI.l Thisr pressure is transj mittedcto:aftable-Itwhich may be supportediny su'ch. a-rnannerfthaty regardlessrof` where on thel tablethe loadis applied; the pull on link 32- will beithesame. Thus4 itl may be carried inconventionalmanner on' fourr feetr I9 having V- shaped. grooves; 20.

2 I. andl`23.:

24. Lever 22 is supported at one end onafcol'- umn` 2.6fcarriedby thefbase'l and hears with its otherendiupon a knife edge 3U. The lever 24 issisupportedV atfone; end on another column 28 carried bythebase- I.

Both levers 22, 24 havethe samedevenratio; that is to say, a certain load applied'l directly above the knife `edge 2l will give the samerreaction: on knife edge-30 as will be obtainedfthereA from the same load if place ydirectlyy over knife-edge` 23.

Thus-the pully on `link- .32 isrproportional'to, out only 'a vfraction -ofytheftotal load imposed onthe specimenffand transmitted through the specimentotheatablen` To further reduce the-forces .acting uponathe indicating mechanism of the'.

testing-machine, another lever 'Zilliy having unequal yarms Vis-.interposed between the load and the scalef'beam.. The connector 32 acts upon knife edges 34 carried by thel lever wvhi-ch is supportedzont knife edges 38; These knife' edges 38 5Il=isfaxlever supportedby knifev edges "Sl on a'v column/52 carriediby thev base extension 2. It

isto -thisrlever sthat the :load just mentioned is transmitted"throughithefrodM in thefcrm of.'

testing.'machine,shown in Fig. 1. Thuspa mo-y ment'fis fcreated'inf-lever 5G which is directlygpro-r portionall to." th'erload on the specimen.. Thisii momentetendsto rotate-ithis leverzin afclockwisezdirection:v Aff'counterweight' 54 is hungfromthe. lever 5B by a knife edge The function of this' counterweightfisfto balance"theiweights. of vari'L ousbeamsf and'levers themselves so` that,vs/'herrv no :loads isappliedtortheispecimen. the vleverxll. will .come torrestlrinrta .balancedposition When-iu.`

The load. is transmitted. throughthese V-shaped 4grooves .onto'knife .edges Theknifeedges' 2.I aref-carried by a'y leverZZ-'and-the knife edges 23 by another lever.

Its' other end transmitsvits load tOJthesameTknife edge 3D upon whichV the lever.` 22 bears.

The lever 36 :almacen:`

a load is applied to a specimen in the testing machine the lever 50 exerts a pressure. on the left hand end 60 of the main scale beam 62 through a scale selecting mechanism which will be described later. The scale beam is supported at 56 upon the post 52 previously mentioned. The scale beam 62 carries a poise 58 which may be moved to balance the pressure applied to the scale beam by the lever 56. A number of scales 202, 263 on the scale beam 62 permit the position of the poise to be read on whichever scale has been chosen by the scale-selecting mechanism.y f

Instead of transmitting pressure on lever 50 by means of the rod 44 actuated by the weighing system just described in connection with Fig. 1 the pressure may be transmitted to lever 50 by a hydraulic system including plunger I'I, as shown` in Fig. 3. The plunger is movable in a cylinder with the space above the ram 1 in cylinder 6. The plunger I1 has a small diameter as compared with the diameter of the ram so that the pres sure exerted by plunger upon the lever 50 is only a traction, but proportional to, the pressure which the ram 1 exerts upon the'specimen I3 through the platen I2. To maintain the load on the specimen and the pressure on the plunger in a fixed ratio it is necessary to provide for frictionless movement of the ram 'I and the plunger Il in their cylinders. This may readily be accomplished by lapping the ram and plunger so that no appreciable quantity of oil will pass either of them, even though no packings or rings are used.

The load balancing mechanism includes a cylinder l which may be supported on post 52. This cylinder contains a piston '|I carried by a piston rod 63, the end of the piston rod moving in a bearing 64 carried by the post 42. The space in the cylinder to the left of the piston 1| is denoted as ||2 and the space to the right of that piston ||3. Keyed to the piston rod 63 is an arm 65 which is connected to the poise 58 by means of a link 61. The pivotal connections of the link 61 are situated in the same plane as the knife edge which supports the scale beam 62 at 56 and the center of gravity of the poise. Therefore, when the poise 58 is moved longitudinally of the scale beam 62 by the cylinder there is no tendency to disturb the balance of the scale beam.

The piston 1| may be moved in the cylinder 10 by oil under pressure which may be supplied by a motor driven pump diagrammatically indicated at 83 which draws oil through a pipe 82 from a sump 84. Oil under pressure is delivered by pump 83 into conduit 86. This connects with conduit 90 that leads to a means to control the rate of flow, generally indicated by a hand controlled valve 92 and to a pressure reducer 88. The valve 92 may be arrangedso that oil'under pressure can be supplied at will either to conduit 9 to push the ram 1 with the platen I2 down on the specimen |3 or to the conduit I0 in order to raise the ram 1. In either case the oil from the opposite side of the ram may ow back through a conduit 04 to the sump 84. Since the pressure in line 90 may vary with Athe resistance encountered by the ram 1, the oil used to move ram 1| passes through thepressure reducer at 88, thereby assuring uniform operation at a constant pressure.

The oil passing through the pressure regulator 88 is carried by a conduit |00 branching into conduits |02 and |04 to a pilot valve |06 and a control valve |08. These valves, which will be more fully describedbelow, control .the iiow ofy oil through conduit |I0 to and from the space ||2 at the left hand side of the piston 1I. Oil under pressure may also be supplied through conduit ||4 to the space |I3 at the right hand side of the piston 1|. This exerts a constant pressure tending to drive this piston toward the left hand position shown. As the left hand face of the piston is larger than the right hand face, when oil is supplied through conduit I I0, the piston 1| will move against the pressure in space H3. The control valve |06 is arranged to feed oil under pressure received through conduit |04 into conduit I0 when the poise is to be moved toward the right. When it is desired to move the poise 58 back to the left the control valve is arranged' to draw oil out through conduit |05lwhich leads back to the sump 84.

The control valve is governed by pilot valvel |06. Referring now to Fig. 2, the pilot valve |06 comprises a cylindrical housing I I9 in which a4 valve piston |20 is vertically movable. The valve piston |20 consists of two sections |2I, |22 joined by a stem |23. Oil under pressure is supplied through conduit |02 to an annular space |28` within the housing ||9 and oil may be drained from a similar annular groove |26 which connects The housing of the control valve |08 may be v fashioned from several sections |42, |44, |46 held `together by through studs whose nuts are visible at |48. These three sections functioning as a single body have bores within which a piston assembly generally indicated at and including a plunger |50 and two valve pistons |52, |53 is y f movable.

A connecting rod |5| connects the plunger |50 with the upper valve piston |52l which in turn is connected by a reduced section |54 with the lower valve piston |53, the latter carrying a lower plunger |56. The space |58 below the plunger |56 is connected through the conduit |30 with the pilot valve |06. |60 and |62 are annular grooves in the housing section |44, the space |60 being connected to conduit |04 and the space |62 to a conduit |05 which communicates with the conduits |I6 and ||8. Whenever the piston |20 of the pilot valve |06 moves in one direction or the other, fluid flows into or out of space |58 for as long a time as the pilot valve is Thus the control valve may be displaced from its illustrated displaced from its neutral position.

respectively in connection with the oil under pressure and the sump are cut oli by the valve pisto |52 and |53.

If the piston assembly |49 of the control valve |08 moves upwardly, oil 'flows from space |60 into line ||0 at a rate dependent upon the vertical displacement of the valve piston |52 and if it moves downwardly, the oil flows back from line ||0 into line ||6 at a rate dependent upon the downward displacement of the valve piston |53.

The valve piston |52 may have grooves `|63 which 1 y9 permit the oil under pressure to pass into a-space |64.` If theplunger '|50 is of smaller diameter than-the val-ve piston |52^there will be a tendency for pushing the valve assembly downwardly, and thereby to drive oilout through line |30 whenever the' pilot valve- |06 permits this.

The movable partsoftthe pilot valvel'06 and of the control valve |03 are interconnected through a `lever |70. lThis'lever is suspended `from the scale beam 62l by means `of'a connector' |72 `linked to the lever |70 at One end ofthe lever |10 is connected at |13 with anextensi'onil of the plunger |50 of the control valve |08 Whereasthe other end of this-lever isconnected'at |15 by means of a rod |16With ayoke "ll whichin turn connects tothe valve stem '|32' of the pilot valve |06. The'length of the two arms a, b ofgthe lever |10 may bear any suitable ratio to each other, the arm a being preferably several times longer than the arm' b.

'If in the position ofthe parts shown inFig. 2, in which there is noilow `of .pressurefluid through conduit |30 .and thus thepiston assembly of the control valve |08 ,is'holding the pivot |13 of the lever |10 in a'xed position, the scale beam 02 starts to-move up ordown, thelever `|10 will first be tilted about|`|3 in the corresponding directions. The-,pilot valve |06 followsthe movement ofthe point H5 of the lever ilflandconnects conduit |30that controls the position of i about its support lll-.causing the valve |06to be t' closed.

Depending .uponlthelramplitude of the-swing ofthe iscale beam, the control valve |08 will have to move vertically a greater orsmallerdistance to close the pilot valve |023. When ,thepilotvalve |06A has closed the,v control valve remains` in whatever position it has reached.

Thuswhenfthefscaleibeam swings:there is la tendency to. open; the pilot valve |00 even for the smallest :swing of .the scale beam,-provided .the pilot valve is working with sufciently low friction to yinsurea .highrsensitivity of' thefsystem. Practically frictlonless lmovement of fthe; pilot valve I 06, which :will allow athisvalve :to Afollow tha slightest .-'tendencviof thezsoale beamato rise or fa1l,:can beobtainedby takingadvantageof the lower frictionf arunning shaft :has as compared with that of, asstaticfshaft. To .maintainrum ning lfriction in arivalve fat `irest af 4device may be provided which imparts an oscillating; movement to themovable parts of: the pilot `valve |06. This device, which-:is bestshowrt ine Figs-.f2 and v',7-',.1com prises anarm |34one end/of whichis-splined to the-"stem |32 :of the `pilot valve s |06 andwhose other `end isl .connectedito fan oscillatingsr'plunger |30 of anvelectric solenoid 1h38. :An automatic makeand Vbreak circuit not shown `keeps-:the plunger oscillating.continuously. This solenoid maybe supported on ,column 42rwhich :also sup-y ports thel pilot `valve .|06iby'- means 'of-a bracket |40. As i has been mentioned before, lthou-,valve stem |32 .is :connectedtovftl'iegzyokey |18., Thisconnection must; bef-(suchlthat the .stem-132 may; be oscillated by the oscillating@ldevicesrjust-:described without oscillating theayoke |118 `orithe'vertical rod 'H5v connected to lever |10. One such connection, by way ofV example, isshown here., 4A: headed stud |80 formstheendof. the valve 'stem |132.y Thisstud can revolveufreelyfn an.opening.rrin'-the yoke |`|8f l0 without interfering'with the axial displacement ofthe yoke |18by the stem |32.

AIt Will be seen that the combination ofthe pilot valve, control valve and scale'beam in this manner provides a vconstruction which will automatically move the poise58 ata rapid rate. or at aslowrate, `depending upon the degree or" unhalance of vthe sc'aievbeam. By this construction I'provide `ample speed for the poise to followahigh rate of loading the specimen without much hunting.

`While the constructionjust'described Will halance the scale beam' where the'load on the specimen is Achanging without'much divergencebetween' theload indicated by the scale reading and the-'load actually limposed on the specimen, even if thescalebeam were to perform Aa relatively considerable swing, I have foundit important to prevent the scale beam lfrom swinging through more than a moderate range for the best results;

`if we study the 'action of the mechanism thus far described, we find'that if the'scale beam is closeto'balancing, the vertical movement of thel connector |12 will be a small one and it will take g only a small `movement of the piston assembly l''l of Athe lcontrolvalve |08 to rclose the pilot valve IME. This'sets the control valve for a low rate'of 4flow into cylinder 10 and a slow rate of movement of the poise 158. When the load'has been balanced, the connector |12 will move in the opposite direction fromthat in' which it moved previously, 'moving the piston valve 20 of the pilot valve Hlt `in lthe opposite direction, and thereby causing the piston assembly M9 of they control valve |08I to'move in the opposite direction merely to shut off the iowof oil to the cylinder 78. Thusthepistonl in the cylinder 'l0 is held againstfurther movement in the position which corresponds tothe 'balancing position of the'poise 58.

Taking another ycase where if the swing of the beam, while still remaining moderate, is greater than has justbcen considered, We lind that connector |12 will move a greater distance and this in turnwillcause the control' valve |49 to be moved a greaterdistance, permitting a larger ilow through line ||0 vand causing a more yrapid movement ofthe poise, so that ythe'beam will again'be balanced in proper time.

It will be'obvious,however, that if the scale beam t2 were allowedA to rise a very considerable distance,'say 2,fand the poise 58 were to be moved tothe position that will balance the beam, the'length of time the scale beam'would need, on

, account offitsinertia, to move down to its neutr-al position ywould cause a flapse of time dur-' ingfwhichthe poise would continue to move. Not until lt'nebeamreaches aflevel position will the poise stop mov-ing. To avoid such4v a and to" secure insteada practically instantaneous reaction of .thel poise tochanges inthe'load, I provide means which limitthe free movement of the' reactingtagainsttheend,of the-levers and apro-f jection 200 onthe posttendfto. turn these levers so that their forward ends 202 willbeforced in! wardly .until .they :bear .against 1 stops`- 20d. on ,post

42. `The.1stops20|ware so'arrangedftlflat in its horizontalA positioni the :scale `beamizZ' has. small free play :beforeitltoucheseither.lever. This play ris irindicated libv rspaces f |34.

lThese .small 1 spaces |84 permit the scale beam to oscillate freely when it approaches its balanced position. If the beam attempts to perform a wide swing, such as when the load is suddenly applied to the specimen, the right end of the scale beam 62 will strike against one of the two fingers 202 and compress one of the springs |98. This prevents the scale beam 02 from going beyond a given maximum amplitude of oscillation even though the poise 58 has not reached the balancing position.

Not only is the inertia time loss thus avoided but the scale beam 62 is pushed back and started in the reverse direction by the end 202 of the respective lever |90 or |92 under the action of a compressed spring |98 as the poise is approaching the balancing point. This gives the scale beam a chance to reach its neutral position and shut off the flow of liquid through conduit ||0 promptly as the poise 58 reaches the balancing position before it can substantially overshoot the balancing point. It would necessarily overshoot if the scale beam had swung up a great distance, such as into the position indicated by the dotted line 20| in Fig. l, and had not started to come back toward the neutral position until the poise had reached the balancing point. In the latter case the iiow oi oil through line ||0 would continue owing into the cylinder all during the time the large inertia scale beam is swinging back towards its horizontal position. By the time the scale beam would reach this horizontal position the poise would be far beyond its proper position on the beam. With the swing limiting device suggested here the hunting just described is effectively eliminated.

By using this device the motion of the scale beam may be reduced so much that it becomes a1- most imperceptible, and a very accurate indication of the instantaneous load on the specimen is obtained regardless of the rate of loading.

Another structural form of the swing limiting means is shown in Fig. 4. Here a cross-arm 230 is pinned to the end of the scale beam 62. The post 42 carries a series of bosses 232 serving as mounts for a plurality of pairs of adjustable stops such as 234, 235. The cross arm 230 carries a number of cantilever springs each spring extending between one pair of stops. One of these cantilever springs 236 is relatively light and extends into the gap between stops 234. Each of the other cantilever springs is somewhat stiffer than the spring which preceded it. Thus spring 238 is stiffer than the spring 236 and this spring extends between the two adjustable stops 235. The stops 234 are so set that for a free oscillating movement of the springl 236 similar spaces |84 are left as are provided for in Fig. 1 for the end of the oscillating beam 62 itself. Thus the scale beam 62 can rise or fall slightly above or below its neutral position within the limits determined by the spaces |84 before one of the stops 234 is touched by the light spring y236. If, however, the swing of the beam is great enough to bring the spring 230 in touch with one of the other of the stops 234 and to subject this spring to an increasing ilexure, the resistance developed by this spring will tend to slow down and reduce the amplitude of movement of the beam. The stops 235 with which the heavier spring 238 cooperated are set back somewhat further than the stops 234 leaving spaces 240 which are somewhat larger than the spaces |84. Should the tendency of the beam to swing be so great that despite the resistance offered by the light spring 236 the beam does not reverse its direction before the heavier spring 238 reaches that stop 235 which lies in the path of the instantaneous movement of the beam, the spring 238 will come to bear against said stop 235 and also become flexed, oiering thereby a much increased resistance to any further movement of the beam in the same direction.

The play aorded by the spaces |84 as well as the spaces 240 may be held as small as a few thousandths of an inch so that the motion of the scale beam may be in a range so small as to be hardly perceptible. Any effect of the inertia of the scale beam is thus largely eliminated. For example, very good results have been achieved with a testing machine having a capacity of 50,000 lbs. in which the spaces |84 were set at .002" and the spaces 240 at approximately .006. In spite of this very limited range of movement of the scale beam 52 the travel speed of the poise 58 varies within a very wide range according to the amplitude of the scale beam displacement. As has been mentioned above, the slightest movement of the scale beam 62, say .001, will open the pilot valve |00 which will then be closed by a responsive movement of the control valve |08, the magnitude of this latter movement being dependent upon the amplitude of said scale beam displacement and also upon the ratio of the arms a and b of the lever |10. If for instance, the scale beam had been out of balance enough to lift cr depress the fulcrum |1| of the lever |10 a distance of .008 (which in the example given would correspond to the heavy springs 238 just touching one of the stops 235) and the ratio of the lever arms a and b were 1:5, the valve piston assembly |49 of the control valve |08 would have to move a distance of .048 in order to close the pilot valve |06. For a movement of the scale beam out of its balanced position corresponding to a vertical movement of the point |1| of say .002", the pilot valve again would open fully but the movement of the control valve to close the pilot valve would cover a distance of .012" only and would thereby l provide for a much slower movement of the poise outside of the cabinet 2|0 over which a pointer 2|2 may move. This pointer may be carried by a shaft 2|3 which is actuated by a pinion or gear 214 meshing with a rack 2|5 that forms part oi', or is connected with the piston rod 63.

It will be seen that due to the swing-limiting device described, the oscillation which any free scale beam has to carry out is sharply damped because when the scale beam swings in either direction and exceeds the small limits of free r movement provided for by the buffer or buffers,

it stresses resilient means so that when the poise approaches the balancing point the scale beam, instead of being at its maximum distance from its neutral position is already moving back toward its neutral position.

In order to provide the machine with several scale ranges, the point at which the load is applied to the scale beam 62 by the lever 50 may be moved to a greater or shorter distance from the scale beam support 56. This point may be @asesinos ifi-3 rconveniently moved by constructing the end 16B fo'f the .beam-62.as "a forkedmember, then slidably ymounting a number of carriers 66 supporting Iknife edges between these forked ends. Eachof these vcarriers 653 is supported on lugs 68 adapted `to* ride upon the upper faces BI of the forked member '50. This permits any desired longi Vtudinal. adjustment of each carrier '66. When the desired position of a particular carrier $6 :has been determined, it may be locked in position -fby Ia Aset screw 95 or in any other convenient manner.

It may be convenient to adjust the position :of .the .carriers :in such a manner that the vary ing lengths of the `divisions of the scale that the poise .must `cover to indicate a given load change when -using one or the other `carrier are simple multiples of each other. Thus, if the carriers which are to be used in connection with scales i262.and 263 are so adjusted that a load which is rbalancedby moving the poise one division on scalef2l2 when the one carrier is effective will require moving the poise one division on scale 263 which is exactly equal to two divisions on scale 262 when the other carrier is effective, one set o'f scale divisions with two sets of numerical values 'might be used in placel of 262 and 263. Inithat case, the scale on the dial 2H traversed bypointerZIZ need have but one set of graduations to permit reading the load according to vseveral scale ranges.

The knife edges are supported on a shaft 91 which extends through holes 96 that areprovided in each of these carriers 66. This shaft may be rotated by any suitable means, such as by a knob 13 carried by a shaft 15 extending across the forked Vend '60 of the scale beam 62. This shaft carries a worm Wheel 1E vmeshing with a worm 1l on the shaft 91.

Akey-way 14 extends lengthwise of the shaft '91. Eccentric disks or cams, each carrying a key fitting in key-way 14 of the shaft are supported in the carriers on the shaft 91 in such a way that though their axial position is determined by the position of the carrier, their angular position is determined by the angular position of 4the shaft. Each eccentric disc carriesra hardened steel ring 80 whose outer surface is ground'so as to form a knife edge 8| extending around the ring.

The eccentrics or cams 19 are sol constructed and arranged on the shaft 91 that their respective portions of maximum eccentricity or radius lie in different radial planes. By turning the knob 13 on the shaft 91 which turns all the ecn centrics or cams 19 keyed to said shaft, any desired eccentric or cam 19 .may be .brought into a Yposition in which its portion of maximum ecn centricity extends in the vertical upward direcn tion. This particular eccentric is then in supporting contact with the lower surface of the lever 50 while the other eccentrics are not `sufficiently elevated to make contact with the lever 50. Further rotating the knob 13 will turn another of the eccentrics into the position in which it supports the lever G. Thus it will appear that the turning of the knob 13 will turn another of the eccentrics into the position in which it supports the lever 56. Thus it will appear that the turning of the knob 13 will cause the several knife edges 8| to be successively elevated into contact with lever 50. Depending upon which knife edge is elevated, the effective length yof the lever arm 50, as measured from the fulorum .termines one scale range.

-56, -"will be 4larger `or smaller. Several scale frangeslare thus .made available.

:have the desired `simple integral relationship.

Itwill be apparent that any other desired ratio may 'be selected with no other restrictions to the positioning of the 'carriers 65 than their own thickness.

vIf lit is desired to increase still further the numberancl the variability of the scale ranges, this may be achieved by combining the selecting device just described with a poise 58 .whose weight may be changed by placing one or 4moreadditionalweights in any convenient manner on the v movable poise. .After the carriers 66 have been adjusted accordinglto .the desired scale ranges, the 'change .froinonefof these ranges'to another can be carried out before the machine is: started as wellas :at .any time during the operation of the machine .without interruption of the test in progress. lSuch a change 'from one Ascale .range to another affects only the indicating'system of -the machine `in'the Vdesiredrnanner without vreacting in any manner upon the load applied to the specimen. This 1in vcontrast to conventional testing machines, :such as the pendulum type, where a changefrom'one scale'range to another requires la change of the weight of the pendulum arm that cannot be madewhile the test is in progress without "creating undesired stresses `in the specimen.

The operation of the machine will readily be .understood f from the description given. The

.specimen to vbe tested I3, 'is mounted in the .machine V:and themotor driven oil pump 83 is started. Thisfwill create a fixed pressure determined. by the pressure regulator 88 `in conduits |09 and' I It. As the 'scale beam is in balance, both val-ves 106 vand m8 are closed and no oil flows .through them. The oilfiowingthrough conduit H4 enters-space H3 in the cylinder'and pushes the piston1! to the leftyca'rrying the poise back toa/zero readingif not already there.

`T ioad is Ano'w'applied to the specimen. This is accomplished by admitting oil under vpressure at a controlled rate into line '9. The admission of .oilintoline 9 may be controlled by known auto'- matic means `.that supply fluid at a constant rate, orfsupply fluid in a variable "quantity to build up the pressureat a constant rate. Such a fluid control apparatus is symbolized Vby hand valve 92. It is .assumed that lthe valve is opened only partly.

Depending upon the vrate 4'at which fluidfis admittedinto space II and the `'commessibility of M the-'specimen I3,r .the head I2 will move Adown slowly-withagradually increasing pressure. In the construction vshown inFigure 1 that pressure is transmitted throughA the table I8 `and the linkage described transmits a proportional smaller force tothe lever 50.

inthe-'construction shown 'in Figure 3, the pressure yof the oil vin space II which varies directly with the load applied to the specimen, transmitsr through line I5 and the small cylinder It .the same 'smaller .proportional force upon lever 50. 1

' In either event lever 59 Vwill be turned clockwise .bearing upon onefof the eccentric cams shownifin Figsf .and 6. .The operator 'will have chosenonefor theother scale by turning .the knob 13 to elevate the particular cam 8| that correspends to the scale range desired. The pressure exerted by lever 50 upon the rear end 60 of lever 62 will tend to lift the right hand end of the lever. When this end of the lever lifts, the link |12 will cause the bar |10 to pivot about the fulcrum |13, at the top of the control valve piston shown in Fig. 2. At this time the control valve cannot move because the pilot valve is in a position that prevents the amount of oil in space |53 either being decreased or increased. It follows that as the right hand end of the bar goes up yoke |18 and connector |16 will also move up.

Current was applied to the solenoid |38 when the test is started. This current is automatically interrupted. by means not shown when the arman ture |35 reaches the end of its stroke so that the armature |36 is rapidly oscillating in and out. This causes the bar |34 which is splined, such as by having a square hole fitting a square shaft |32, to turn the valve back and forth through a small angle.

When the yoke moves up the valve |20 also moves up. Thereby a connection is made between the oil under pressure available in line |02 through conduit to space |58. The control valve |49 now starts to move upward at a slow rate determined by the degree that valve |2| uncovered the opening into conduit |02. As the valve |49 moves upwards, the lever |10 now swings about |1| thus bringing the pilot valve |20 back. As the pilot valve comes back the control valve moves more slowly but finally it will have moved iar enough to again close pilot valve |00.

The control valve is now in a position to admit i oil under pressure from line |04 into line ||0 at a fixed rate. This iixed rate will depend upon the position in which the control valve |49 stands and this in turn is dependent upon the amplitude of the upward swing oi scale beam pendulum 62.

Oil flowing through line ||0 now enters space ||2 at the left hand end of the piston. Since that face is larger than the face against space |3, the piston 1| will move to the right the pressure of the oil on the larger face |2 forcing the oil out l of space I|3 back through line ||4. The movement of the piston carries with it the arm 65. Through a link 01 which is preferably placed in the plane of the fulcrum 56 and the center of gravity of the poise 50, the poise is moved toward f the right at a uniform rate. At the same time a rack 2|5 turns a pinion 2|4 on shaft 2|3 and this in turn moves the pointer 2 |'2 indicating the load on a circular scale. It is obvious that a recording device could be attached either to rod 2 5 or to shaft 2 |3 and if such a device is so attached, a graphic record of the change in load may be secured. As the poise 58 approaches the point where the scale beam will again balance. the point |1| connected with the end of the scale beam moves downward. Since the control valve is at this time locked in an open position the pilot valve |20 moves downward connecting the conduit |30 with passage i0 back to the sump. As a result the pilot valve moves down, cutting down the rate of flow and slowing up the rate at which the poise moves as the balancing point is approached. When the balancing point is reached, the poise is moving very slowly and it will not appre-ciably overshoot the balancing point.

Sometimes the load on the specimen |3 changes very rapidly. The resistance of the specimen to compression or tension might have been slight up to a certain point but increased rapidly from there on. As a result the scale beam 62 may lll lcc

suddenly desire to swing up to a position siicli as that shown in dotted lines at 20| in Fig. l. In that event, when the scale beam has moved up'- ward a small distance, |84 in Fig. l, it will contact a finger 202 of lever |00. This linger will back olf somewhat compressing the spring |90. The increasing resistance to the movement of the scale beam will bring it to a stop only a short distance above its balancing position.

Since the scale beam has now moved upwards a maximum distance a pilot valve |06 will be opened its maximum distance. As oil flows through line |30 into space |58 the control valve will open, and it will continue to open until it also has opened its maximum distance and shut oilc the pilot valve. The poise will now be impelled forward at its maximum speed by the piston 1|. When the poise is some distance from the balancing point the force of the compressed spring added to the force of the poise will bring the scale beam back down to the point where linger 202 bears against stop 204. The centering movement of the scale beam thus accomplished acting upon the lever |10 in a manner already described, will cause the control valve to cut down the rate of feed of oil into space I2. Thus the poise approaches its balancing position more slowly. We now have the condition first described in which the scale beam is swinging freely within the limits |04 and as the poise continues to approach its balancing point its speed will be further reduced. Even though the poise started out at the speed that might be expected to cause a serious overshooting of the mark its rate of movement is thereby automatically so controlled that it will approach the balancing point without appreciably overshooting the mark.

While in the .foregoing description I have described my nvention with reference to several specific embodiments and with reference to its application to particular forms of machines having an indicating system of the scale-beam type, it is to be understood that these particular con# structional embodiments and applications have been given as illustrative examples only, since various changes and modifications may be made without departing from the spirit of the invention or the scope of' the appended claims.

The principle of using a pilot controlling the main controller which regulates the speed of the poise travel, also the principle of limiting the oscillation by restraining elements that still allow a limited free oscillation has been illustrated by a hydraulic control; it could just as well be a pilot resistance controlling the movement of a larger resistance that determines the speed of a motor moving a poise.

It will be obvious for instance, that instead of. using the plunger |1 in Fig. 3 for transferring to the lever 50 a load proportional to the iiuid pressure existing in the space il in a cylinder 0, a chamber communicating with said space and closed by a movable diaphragm could be provided, which diaphragm would operate some member adapted to operate the lever 50. Further, instead of providing differential pistons 10 and |40 as has been described, the return movement of these pistons could be carried out by means of springs, etc.

What I claim is:

l. A load indicating testing machine comprising a scale beam, a poise movable on said scale beam for balancing a load proportional to the load applied to the specimen to be tested, hydraulic means for moving said poise on said scale Aacomode yinglyarranged in said cylinder and operatively connected to Said poise, a pilot valve, a control valve operable'by said pilot valve for admitting pressure fluid to said cylinder, the speed of the movement of said poise on said beam being determined by the amount'of pressure fluid admitted to said cylinder by said control valve, said pilot valve rand `said control valve being mechanically yconnected lto each other and to saidscale beam so as to impart a wide opening movement to said pilot valve in response to any swingof said scale beam out of its neutralposition, while permitting said control valve to be opened hydraulically to a greater or smaller Vextent commensurate with the-larger or smaller-instantaneous amplitude of said-swing.

2. A load indicating testing machine comprising a scale beam, a poise movable on said scale beam for balancing a loadv proportional to the admitted to said cylinder by said control valve in relation tothe varying yamplitude of the swing of said beam,said control valve havinga differentialpiston so as tojprovide a constanthydraulic force tending to move said control valve intona position in which it interrupts the admission, of pressure Vfluid to said cylinder.

3. A loadindicating testing'machine comprising a scale beam, a poise, movable on said scale beam for balancing a load proportional tothe load applied to the specimen to be tested., lhydraulic means for moving said poise on saidscale beam-including a cylinder and operatively connected to said poise, a-pilot valve, acontrol valve operable `by said pilot valve for admitting. pressure fluidto said cylinder, the speed of themovement of said-poise on said beam beingdetermined by the amount of pressure fluid 'admitted tosaid cylinder by said. control valve, said pilotvalve and said control valve beingmechanically connected to each other and to said scale beamsoas to impart a wide opening movementtosaid pilot valvein response to any swing of said .scale beam out ofv its neutral position while permitting said control Valve to be opened hydraulically to Ia greater or smallerextent commensurate ,with the larger or smallerginstantaneous amplitude of said swing, and saidcontrol valve havinga differential piston'so as to provide a constant hydraulic force tending to return said control valve to Athe position in whichit interrupts the admission of pressure lfluid to said cylinder.

4. A load indicating Vtesting machine comprising a scale beam, a poise` movableon said scale beam for balancingga load proportional to the load applied to the specimen to be tested, ,hydraulicmeans for movingisaid poise von said scale beam including a cylinder,` a piston reciprocatingly arranged 'in said: cylinder, apiston rod .attached to said pistonand operatively connected to said poise, a pilot valve, a control valve operable by said pilot valve'for admitting pressure fluid to saidcylinder, the' speed of the movement of said'poise von said beambeing determined by the amount of pressure-huid admitted to said cylinder by said control valve, said pilot valve and l 8 said'control valve being mechanically connected to each other and to said scale beam so as to impart a wide opening movement to said pilot valve in response to any swing of saidv scale beam out of its neutral position, while permitting said control valve to be opened hydraulically to a greater or smaller extent commensurate with the larger .or smaller instantaneous amplitude of said swing, a housing enclosing said scale beam, said poise and said hydraulic means for movingsaidpoise, adial and a pointer outside of said housing, and a gear for actuating' said pointer, part of this gear ,being formed by a rack carried by an extension of said piston rod.

5. In combination with a scale beam, a swingable lever adapted to apply load to said beam by bearing against the latter, a plurality of elements carried by VSaid beam at different points of the length thereof, means for moving arbitrarily any desired one of said elements in a plane perpendicular to the lengthwise direction 0f, Said beam into contact with said lever, each of said elements being adjustable also lengthwise of said beam.

6. In combination with a scale beam, `a swingable lever adapted to apply load to said beam by bearing against the latter, a shaft supportedby said beam ,and extending in the lengthwise` direction thereof, a plurality of elements on said shaft having each a peripheral portion extending farther from the axis of saidl shaft than other portions, and said elementsl being .mounted at different kpoints of the length .of the shaft vin sucha manner that their portions vof maximum radius lie in different radial planes and by turning said shaft any desired one of said-elements may be brought into supporting contact with said lever.

7. In combination with a scale beam, aswingable lever adapted toy apply load to said beam `by bearing `against the latter, a shaft supported by said beam-and extending in the lengthwise direction thereof, a plurality of elements on said shaft havingeach aperipheral portion extending farther from theaxisof said shaft than other portions,vand said elements being mounted at different points of the length of said shaft in such aimannerl that their portions of maximum radius lie Yin different radial planes and by turning said shaft any desired one of said elements may be brought ,into supporting contact with said lever, each `of said elements being adjustable lengthwise on said shaft.

8. 'In a testing machine having a load indicatingk system of the scale-,beam vtype,.a scale range changing device comprising means for applying to thescale beam of said load `indicating system a loadproportional to the load ,applied to the specimen to be tested, anda plurality of elements mountedon said beam atdifferent distances from the fulcrum thereof together with means for varying the .moment determining the .length of the, load arm. of said beamfby transferring the point of load application from one toanotherof said plurality elements.

9. In a testing machine having a load indicating system of the-,scale-beam type, a scale yrange changing device comprising means for applying to the scale .beam of saidload indicating system a load proportional to the-,load applied to the specimen to be tested, and a plurality of elements carriedby said beam together with means for varying the moment determining length of the load arm of saidbeam by transferring the point of load application from one to another of said plurality of elements, each of said elements being adjustable in the longitudinal direction of said beam.

10. In a testing machine having a load indicating system of the scale beam type, a scale range changing device comprising a swingable lever adapted to apply to the beam of said. load indicating system a load proportional to the load applied to the specimen to be tested bearing upon said beam, a shaft supported by said beam and extending in the lengthwise direction thereof, a

plurality of elements on said shaft having each a peripheral portion extending farther from the axis of said shaft than other portions and said elements being mounted at different points of the length of said shaft in such a manner that the portion of maximum radius of each element lies in a different radial plane and by turning said shaft any desired of said elements may be brought into supporting contact with said lever.

l1. In a testing machine having a load indicating system of the scale beam type, a scale range changing device comprising a swingable lever adapted to apply to the beam of said load indicating system a load proportional to the load applied to the specimen to be tested by bearing upon said beam, a shaft supported by said beam and extending in the lengthwise direction thereof, a plurality of elements on said shaft having each a peripheral portion extending farther from the axis of said shaft than other portions and said shaft any desired of said elements may be brought into supporting Contact with said lever, each of said elements being adjustable lengthwise on said shaft.

12. In a testing machine having a load indicating system of the scale-beam type, a scale range changing device comprising a swingable lever adapted to apply to the beam of said load indicating system a load proportional to the load applied to the specimen to be tested by bearing upon said beam, a shaft supported by said beam and extending in the lengthwise direction thereof, a plurality of circular elements being eccentrically mounted on said shaft at different points of the length thereof in such a manner that the `portion of maximum eccentricity of each element lies in a different radial plane so that by turning said shaft any desired of said elements may be brought into supporting contact with said lever.

13. In a testing machine having a load indicating system of the scale-beam type, a scale range changing device comprising a swingable lever adapted to apply to the beam of said load indicating system a load proportional to the load applied to the specimen to be tested by bearing upon said beam, a shaft supported by said beam and extending in the lengthwise direction thereof, a plurality of cams mounted on said shaft at different points of the length thereof in such a manner that the portion of maximum radius of each cam lies in a different radial plane so that by turning said shaft any desired of said cams may be brought into supporting contact with said lever.

14. In a testing machine having a load indicating system of the scale-beam type, a scale range changing device comprising a swingable lever adapted to apply to the beam of said load indicating system a load proportional to the load applied to the specimen to be tested by bearing upon said beam, a shaft supported by said beam and extending in the lengthwise direction thereof, a plurality of circular elements, each formed as a knife edge at its circumference, eccentrically mounted on said shaft at different points of the length thereof in such a manner that the portion of maximum eccentricity of each element lies in a different radial plane so that by turning said shaft the knife edge of any desired of said eccentric elements may be brought into supporting contact with said lever whereas the knife edges of all the other eccentric elements are held out of contact with said lever.

15. In a testing machine having a load indicating system of the scale-beam type, a scale range changing device comprising a swingable lever adapted to apply to the beam of said load indicating system a load proportional to the load applied to the specimen to be tested by bearing upon said beam, a shaft supported by said beam and extending in the lengthwise direction thereof, a plurality of cams, each formed as a knife edge at its circumference, mounted on said shaft at different points of the length thereof in such a manner that the portion of maximum radius of each cam lies in a different radial plane so that by turning said shaft the knife edge of any desired of said cams may be brought into supporting contact with said lever whereas the knife edges of all the other cams are held out of contact with said lever.

16. In a testing machine in which the load is applied to the specimen to be tested by means of hydraulic pressure produced in a cylinder and the load indicating system is of the scale-beam type, a member movable under the action of hydraulic pressure derived from said cylinder, a swingable lever operable by said member and bearing against the beam of said load indicating system so as to apply to said beam a load proportional to the load applied to the specimen to be tested, a poise on said beam, and means for moving said poise on said beam at a. variable speed controlled by means responsive to variations in the degree of unbalance of said beam.

17. In a testing machine in which the load is applied to the specimen to be tested by means of hydraulic pressure produced in a cylinder and the load indicating system is of the scale-beam type, a member movable under the action of hydraulic pressure derived from saidl cylinder, a swingable lever operable by said member and bearing against the beam of said load indicating system so as to apply to said beam a load proportional to the load applied to the specimen to be tested, a poise on said beam, and hydraulic means for moving said poise on said beam at a variable speed controlled by hydraulic means responsive to variations in the degree of unbalance of said beam.

18. A load indicating testing machine comprising a scale beam, a poise movable on said scale beam for balancing a load proportional to the load applied to the specimen to be tested, means for moving said poise on said scale beam at a variable speed controlled by hydraulic means including a` pilot valve and a control valve, each having a. movable valve piston, said pilot valve being constructed to open in response to any swing of said scale beam out of its neutral position while becoming closed upon said control valve having opened to an extent commensurate with the larger or smaller instantaneous amplitude of said swing, and means for oscillating said valve pistton of said pilot valve about its axis at a rapid ra e.

19. A load indicating testing machine comprising a scale beam, a poise movable on said scale beam for balancing a load proportional to the load applied to the specimen to be tested, hydraulic means for moving said poise on said scale beam including a cylinder reciprocatingly arranged in said cylinder and operatively connected to said poise, a pilot valve, a control valve operable by said pilot valve for admitting pressure uid to said cylinder, the speed of the movement of said poise on said beam being determined by the amount of pressure duid admitted to said cylinder by said control valve, said pilot valve and said control valve having each a movable valve piston, a lever system connecting said valve pistons to each other and to said scale beam so as to impart an opening movement to the valve piston of said pilot valve in response to any swing of said scale beam out of its neutral position, while permitting said control valve to be opened hydraulically to a greater or smaller extent commensurate with the larger or smaller instantaneous amplitude of said swing, and means for oscillating said valve piston of said pilot valve about its axis at a rapid rate.

20. A load indicating testing machine comprising a scale beam, a poise movable on said scale beam for balancing a load proportional to the load applied to the specimen to be tested, hy-

draulic means for moving said poise on said scale beam including a cylinder, a piston reciprocatingly arranged in said cylinder and operatively connected to said poise, a pilot valve, a control Valve operable by said pilot valve for admitting pressure fluid to said cylinder, the speed of the movement of said poise on said beam being determined by the amount of pressure fluid admitted to said cylinder by said control valve, said pilot valve and said control valve having each a movable valve piston, a lever system connecting said valve pistons to each other and to said scale beam so as to impart an opening movement to said pilot valve in response to any swing of said scale beam out of its neutral position, while permitting said control valve to be opened hydraulically to a greater or smaller extent commensurate with the larger or smaller instantaneous amplitude of said swing, means for oscillating said valve piston of said pilot valve about its axis at a rapid rate, and coupling means inf serted into the connection between said oscillating piston and said lever system permitting said pilot valve piston to follow movements of said lever system without transferring the oscillating movements of said pilot valve piston to said lever system.

21. A load-indicating testing machine comprising a scale beam, a poise movable on said scale beam to balanceV a load that is proportional to the varying load applied to the specimen to be tested, means for moving said poise along said scale beam and means causing said last-named means to move the poise toward the balanced position of the beam at a rate determined by the divergence of said beam from its balanced position at any instant.

22. A load-indicating testing machine comprising a scale beam, a poise movable on said scale beam to balance a load that is proportional to the varying load applied to the specimen to be tested, hydraulic means for moving said poise along said scale beam, and hydraulic control means causing said last-named means to move the poise toward the balanced position of the beam at a rate determined by the divergence of 22 said beam from its balanced position at any instant.

23. A load-indicating testing machine comprising a scale beam, a poise movable on said scale beam to balance a load that is proportional to the varying load applied to the specimen to be tested, means for moving said poise along said scale beam and means causing said last-named meam. to move the poise toward the balanced position of the beam at a rate determined by the divergence of said beam from its balanced position at any instant and resilient means adapted to assist the poise in balancing the load by supplying a restoring force, which increases with the divergence of the beam from its balanced position, said resilient means being engaged by the scale beam only after1 the scale beam reaches the limits of a range Within which it can oscillate unrestrainedly.

l 24. A load-indicating testing machine comprising a scale beam, a poise movable on said scale beam for balancing a load transmitted to the scale beam that is proportional to the load applied to a specimen to be tested, hydraulic means for moving said poise along said scale beam including a cylinder, a piston in said cylinder operatively connected to said poise, a control valve determining the rate at which liquid ilovvs into the cylinder, a plunger adapted to progressively open the control valve, a pilot valve actuated by the scale beam and a conduit from the pilot valve to the plunger to progressively open the control valve While the scale beam remains out of balance.

25. A load-indicating testing machine comprising a scale beam, a poise movable on said scale beam for balancing a load transmitted to the scale beam that is proportional to the load applied to a specimen to be tested, hydraulic means for moving said poise along said scale beam including a cylinder, a piston in said cylinder operatively connected to said poise, a control valve determining the rate at which liquid iiows into the cylinder, a plunger adapted to progressively open the control valve, a pilot valve actuated by the scale beam, a conduit from the pilot valve to the plunger to progressively open the control valve While the scale beam remains out of balance, a pinion-controlled pointer and a rack moved by the piston engaging the pinion to give a dial reading corresponding to the poise position on the scale.

26. In a testing machine wherein the load on a specimen is indicated by the position of the poise relative to a scale on the scale beam, in combination, a housing, means for applying a load to the specimen, a pivoted arm supported by the housing, means for transferring a predetermined part of the load applied to the specimen to the pivoted arm, a scale beam having an arm extending alongside of the pivoted arm, a plurality of knife edges spaced along said arm of the scale beam, the otherarm of the scale beam being provided With scales of different ranges, a poise movable on said other arm to balance the scale beam the position of the poise being readable on the scales, means permitting the selection of any one of said knife edges to transmit the load from the specimen through the pivoted lever to the scale beam thereby changing the scale which indicates the load on the specimen.

27. A load-indicating testing machine comprising a scale beam, a poise movable along asid scale beam for balancing a load which is proportional to the stress applied to the specimen being tested,

acca-'ooe hydraulic means for moving said poise along said scale beam including a cylinder, a piston in said cylinder operatively connected to said poise, a two-way hydraulically operated control valve adapted to add or withdraw liquid from the cylnder, a two-way pilot valve operated by the beam to deliver iiuid to move the control valve to such an extent and direction that it will deliver or withdraw liquid from the cylinder at a rate proportional to the extent of swing of the scale beam to cause the piston to move the poise in the direction tareduce the swing of the beam.

28. A load-indicating testing machine comprising a scale beam, a poise movable along said scale beam balancing a load which is proportional to the stress applied to the specimen being tested, hydraulic means for moving said poise along said scale beam including a cylinder, a piston in said cylinder operatively connected to said poise, a two-way hydraulically operated control valve adapted to add or withdraw liquid from the cylinder, a two-way pilot valve operated by the beam to deliver uid to move the control valve to such an extent and direction that it will deliver or withdraw liquid from the cylinder at a rate proportional to the extent of swing of the scale beam to cause the piston to move the poise in the direction to reduce the swing of the beam. means to progressively close the pilot valve as the control valve is opened by the pilot valve.

29. In a load balancing device, in combination, a lever having a horizontal fulcrum, means for applying a vertical load to said lever at a fixed distance trom said fulcrum, a second fulcrum parallel to the first fulcrum and horizontally spaced therefrom, an arm pivoted on said axis movable in the vertical plane of said lever, a plurality of devices spaced at xed intervals between the iulcra and movable in a plane parallel. thereto, each device being so designed that any selected device may transmit a force from the lever to the arm, means for selectively moving one of said devices into position between the lever and the arm. and means connected with the arm for balancing the force transmitted through said selected device.

3G. A testing machine adapted to indicate the load applied to a specimen comprising, in combination, a scale beam free to swing above and below its balanced position, a frame supporting the bean stops on the frame spaced from the free end oi' the beam, mechanism for loading the scale beam. in a fixed ratio to the stress applied to a specimen being tested, a poise movable on the scale beam to balance the beam, a rst resilient means carried by the scale beam which engages one of said stops after the free end of the scale beam has moved through a predetermined distance from its balanced position `and which is increasingly stressed by the further movement of the scale beam relative to the stop and thereby opposes the swing of the scale beam with increasing force, a second means less resillll ient than the first carriedby the scale-beam which engages another stop after the free end of the scale beam has moved through a yfixed distance larger than the predetermined distance so that further movement of the scale beam is re-f sisted by the force required to increasingly/ stress each of said two resilient means.

31. In a load-balancing device, in combination, two generally parallel levers movable in a vertical plane, a horizontal iulcrum about which the first lever pivots, a second fulcrizim horizontally spaced from said iirst fulcrum about which the second lever pivots, a plurality of devices each movable in its own plane located at a fixed interval yin the distance between the t o fulcra, means for moving any one of said d lvices into position within its ownplane to transmit pressure Jfrom the first to the second lever, means for applying a load to be measured tothe iirst lever, means connected with the second lever ,for balancing said load through said selected device.

32. ln a testing machine having parallel scales each of which is adapted for indicating loads in making tests within ,a different load range, in combination, means for exerting alarge force on a specimen, a lever balanced, on a fulcrumjmeans exerting a stress proportionate to the large force exerted on the specimen upon one arm of the lever, other means creating aksmall force acting upon the other arm of said lever, means for changing the ratio which the lever arm on which the small force acts bears to the lever arm on which said stress acts, means for measuring thev small force having an Aindicator moving a distance proportionate to the size of said force, and a plurality of scales in operative relation to said indicator and each calibrated to permit the indicater to indicate the size of the large load which is balanced by the small force when the correspending lever arm ratio has been chosen.

FRANCIS C. HUYSER.

CITED The ioliowingreferences are of record in the file of `this patent:

UNITED STATES PATENTS 

